Latent scratches are extremely shallow scratches inevitably introduced during chemical mechanical polishing (CMP), which deteriorates the performance of functional crystals. Although latent scratches can currently be detected by some advanced microscopes, there is still a lack of in-depth understanding of them. In this paper, we describe the morphological characteristics of latent scratches using atomic force microscopy and develop a mathematical model to explain the formation mechanism of latent scratches with YAG crystals as an example. The observations showed that the distributions of the depth and width of latent scratches were always Gaussian-like. And the pressure was positively correlated with the number of latent scratches but did not significantly affect the depth and width. The proposed mathematical model describes the contact state between the particles and the crystal surface, and identifies the formation of latent scratches resulting from plastic deformation of the crystal surface, a conclusion further supported by transmission electron microscopy observations. The model also explains that the distribution of depth and width is mainly determined by the material properties and that pressure affects the number of particles in contact with the workpiece but does not significantly change the contact stress between individual particles and the workpiece. There is an upper limit to the contact stress, resulting in scratches always below 1 nm in depth. The analysis of latent scratches is of great significance to removing latent scratches and manufacturing the ultra-smooth surface in the CMP process.

潜在划痕是化学机械抛光（CMP）过程中不可避免地引入的极浅划痕，它会降低功能晶体的性能。虽然目前一些先进的显微镜可以检测到潜在的划痕，但仍然缺乏对它们的深入了解。在本文中，我们使用原子力显微镜描述了潜在划痕的形态特征，并建立了一个数学模型，以 YAG 晶体为例来解释潜在划痕的形成机制。观察表明，潜在划痕的深度和宽度分布始终呈高斯分布。压力与潜在划痕的数量呈正相关，但对深度和宽度没有显着影响。所提出的数学模型描述了颗粒与晶体表面之间的接触状态，并确定了晶体表面塑性变形导致的潜在划痕的形成，透射电子显微镜观察进一步支持了这一结论。该模型还解释说，深度和宽度的分布主要由材料特性决定，压力会影响与工件接触的颗粒数量，但不会显着改变单个颗粒与工件之间的接触应力。接触应力有上限，导致划痕深度始终低于 1 nm。潜在划痕的分析对于CMP工艺中去除潜在划痕和制造超光滑表面具有重要意义。